Annular optical spacer, imaging lens module, imaging apparatus and electronic device

ABSTRACT

An annular optical spacer includes a first side portion, a second side portion, an outer annular portion and an inner annular portion. The second side portion is disposed opposite to the first side portion. The outer annular portion connects the first side portion and the second side portion. The inner annular portion connects the first side portion and the second side portion, wherein the inner annular portion is closer to a central axis of the annular optical spacer than the outer annular portion. The inner annular portion includes a plurality of annular grooves, wherein the annular grooves are disposed coaxially to the central axis, and each of the annular grooves includes a plurality of stepped surfaces.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number104208271, filed May 27, 2015, which is herein incorporated byreference.

BACKGROUND

Technical Field

The present disclosure relates to an annular optical spacer and animaging lens module. More particularly, the present disclosure relatesto an annular optical spacer and an imaging lens module which isapplicable to portable electronic devices.

Description of Related Art

Due to the popularity of personal electronic products and mobilecommunication products having camera functionalities, such as smartphones and tablet personal computers, the demand for compact imaginglens modules has been increasing, and the requirements for highresolution and image quality of present compact imaging lens modulesincrease significantly.

An optical spacer is generally used to provide an optical space betweenany two lens elements in an imaging lens module. A surface property ofthe optical spacer relates to an effect of suppressing unexpectedlights. Accordingly, an image quality of the imaging lens module isinfluenced by the surface property of the optical spacer.

A conventional optical spacer is typically manufactured by an injectionmolding method. The optical spacer has a smooth and bright surface,which is featured with high reflectivity. As a result, the conventionaloptical spacer cannot suppress unexpected lights.

Another conventional optical spacer is provided for suppressingunexpected lights. The conventional optical spacer is atomized with asurface treatment, so that a reflectivity thereof is reduced. However,the effect of suppressing unexpected lights is still limited. Therefore,the conventional optical spacer cannot satisfy the requirements ofhigh-end optical systems with camera functionalities.

Given the above, how to improve the surface property of the opticalspacer for enhancing the image quality of compact imaging lens moduleshas become one of the important subjects.

SUMMARY

According to one aspect of the present disclosure, an annular opticalspacer includes a first side portion, a second side portion, an outerannular portion and an inner annular portion. The second side portion isdisposed opposite to the first side portion. The outer annular portionconnects the first side portion and the second side portion. The innerannular portion connects the first side portion and the second sideportion, wherein the inner annular portion is closer to a central axisof the annular optical spacer than the outer annular portion. The innerannular portion includes a plurality of annular grooves, wherein theannular grooves are disposed coaxially to the central axis, and each ofthe annular grooves includes a plurality of stepped surfaces.

According to another aspect of the present disclosure, an imaging lensmodule includes a barrel, a lens assembly, and an annular opticalspacer. The lens assembly includes a plurality of lens elements disposedin the barrel. The annular optical spacer disposed in the barrel andconnects to at least one of the lens elements. The annular opticalspacer includes a first side portion, a second side portion, an outerannular portion, and an inner annular portion. The second side portionis disposed opposite to the first side portion. The outer annularportion connects the first side portion and the second side portion. Theinner annular portion connects the first side portion and the secondside portion, wherein the inner annular portion is closer to a centralaxis of the annular optical spacer than the outer annular portion. Theinner annular portion includes a plurality of annular grooves, whereinthe annular grooves are disposed coaxially to the central axis, and eachof the annular grooves includes a plurality of stepped surfaces.

According to another aspect of the present disclosure, an imagingapparatus includes the imaging lens module according to the foregoingaspect.

According to another aspect of the present disclosure, an electronicdevice includes the imaging apparatus according to the foregoing aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of an annular optical spacer according tothe 1st embodiment of the present disclosure;

FIG. 1B shows a top view of the annular optical spacer in FIG. 1A;

FIG. 1C is a sectional view of the annular optical spacer along line1C-1C in FIG. 1 which shows the parameters φ1 and φ2 according to the1st embodiment.

FIG. 1D is an enlarged view of part 1D in FIG. 1C which shows theparameters D, h and d according to the 1st embodiment;

FIG. 1E shows a schematic view of the parameter θ according to the 1stembodiment;

FIG. 2A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 2nd embodiment of the presentdisclosure;

FIG. 2B is an enlarged view of part 2B in FIG. 2A which shows theparameters D, h and d according to the 2nd embodiment;

FIG. 2C shows a schematic view of the parameter θ according to the 2ndembodiment;

FIG. 3A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 3rd embodiment of the presentdisclosure;

FIG. 3B is an enlarged view of part 3B in FIG. 3A which shows theparameters D, h and d according to the 3rd embodiment;

FIG. 3C shows a schematic view of the parameter θ according to the 3rdembodiment;

FIG. 4A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 4th embodiment of the presentdisclosure;

FIG. 4B is an enlarged view of part 4B in FIG. 4A which shows theparameters D, h and d according to the 4th embodiment;

FIG. 4C shows a schematic view of the parameter θ according to the 4thembodiment;

FIG. 5A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 5th embodiment of the presentdisclosure;

FIG. 5B is an enlarged view of part 5B in FIG. 5A which shows theparameters D, h and d according to the 5th embodiment;

FIG. 5C shows a schematic view of the parameter θ according to the 5thembodiment;

FIG. 6A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 6th embodiment of the presentdisclosure;

FIG. 6B is an enlarged view of part 6B in FIG. 6A which shows theparameters D, h and d according to the 6th embodiment;

FIG. 6C shows a schematic view of the parameter θ according to the 6thembodiment;

FIG. 7A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 7th embodiment of the presentdisclosure;

FIG. 7B is an enlarged view of part 7B in FIG. 7A which shows theparameters D, h and d according to the 7th embodiment;

FIG. 7C shows a schematic view of the parameter θ according to the 7thembodiment;

FIG. 8A is a schematic view of an annular optical spacer and theparameters φ1 and φ2 according to the 8th embodiment of the presentdisclosure;

FIG. 8B is an enlarged view of part 8B in FIG. 8A which shows theparameters D, h and d according to the 8th embodiment;

FIG. 8C shows a schematic view of the parameter θ according to the 8thembodiment;

FIG. 9A is a schematic view of an annular optical spacer and theparameters φ1, φ2 and D according to the 9th embodiment of the presentdisclosure;

FIG. 9B is an enlarged view of part 9B in FIG. 9A which shows theparameters h and d according to the 9th embodiment;

FIG. 9C shows a schematic view of the parameter θ according to the 9thembodiment;

FIG. 9D is an enlarged view of part 9D in FIG. 9A which shows theparameters h and d according to the 9th embodiment;

FIG. 9E shows another schematic view of the parameter θ according to the9th embodiment;

FIG. 10 shows an imaging lens module according to the 10th embodiment ofthe present disclosure;

FIG. 11 shows an electronic device according to the 11th embodiment ofthe present disclosure;

FIG. 12 shows an electronic device according to the 12th embodiment ofthe present disclosure; and

FIG. 13 shows an electronic device according to the 13th embodiment ofthe present disclosure.

DETAILED DESCRIPTION 1st Embodiment

FIG. 1A is a schematic view of an annular optical spacer 100 accordingto the 1st embodiment of the present disclosure. FIG. 1B shows a topview of the annular optical spacer 100 in FIG. 1A. FIG. 1C is asectional view of the annular optical spacer 100 along line 1C-1C inFIG. 1 which shows the parameters φ1 and φ2 according to the 1stembodiment. In the 1st embodiment, the annular optical spacer 100includes a first side portion 110, a second side portion 120, an outerannular portion 130 and an inner annular portion 140.

The second side portion 120 is disposed opposite to the first sideportion 110. The outer annular portion 130 connects the first sideportion 110 and the second side portion 120. The inner annular portion140 connects the first side portion 110 and the second side portion 120,wherein the inner annular portion 140 is closer to a central axis of theannular optical spacer 100 than the outer annular portion 130. The innerannular portion 140 includes a plurality of annular grooves 150, whereinthe annular grooves 150 are disposed coaxially to the central axis, andeach of the annular grooves 150 includes a plurality of stepped surfaces(its reference numeral is omitted). Therefore, it is favorable forreducing the reflected lights effectively so as to improve the imagequality.

In details, the annular optical spacer 100 can be made of black plasticmaterial and manufactured by an injection molding method. Therefore, itis favorable for the annular optical spacer 100 applied to the compactlenses.

The annular grooves 150 and the annular optical spacer 100 can be formedintegrally. Therefore, it is favorable for maintaining the conveniencesof manufacturing so as to be suitable for the mass production.

The first side portion 110 and the second side portion 120 can includean abutting surface 111 and an abutting surface 121 respectively, andthe abutting surfaces 111, 121 are both flat and orthogonal to thecentral axis of the annular optical spacer 100. Therefore, when theannular optical spacer 100 is applied to the imaging lens modules, it isfavorable for keeping stable abutting strength among the optical spacersof the imaging lens modules so as to maintain the image quality of theimaging lens modules.

In the 1st embodiment, when an outer diameter of the annular opticalspacer 100 is φ1, and an inner diameter of the annular optical spacer100 is φ2, the following condition can be satisfied: 0.40<φ2/φ1<0.90.Therefore, it is favorable for the annular optical spacer 100 applied tothe compact lenses.

FIG. 1D is an enlarged view of part 1D in FIG. 1C which shows theparameters D, h and d according to the 1st embodiment. In the 1stembodiment, the inner annular portion 140 includes the annular grooves150, wherein the annular grooves 150 are disposed coaxially to thecentral axis, and each of the annular grooves 150 includes the steppedsurfaces. When a distance between an end closest to the central axis andan end farthest away from the central axis of the annular grooves 150 isD, an outer diameter of the annular optical spacer 100 is φ1, and aninner diameter of the annular optical spacer 100 is φ2, the followingcondition can be satisfied: 0.15<2D/(φ1−φ2)<0.80. Therefore, it isfavorable for improving the design conveniences of the annular opticalspacer 100 so as to reduce the design difficulties.

In the 1st embodiment, when a number of the annular grooves 150 is N1,the following condition can be satisfied: 2≦N1≦50. Therefore, it isfavorable for maintaining the effects of reducing the reflected lightsof the stepped surfaces of the annular grooves 150. Preferably, thefollowing condition can be satisfied: 2≦N1≦10.

In the 1st embodiment, the stepped surfaces of each of the annulargrooves 150 include a plurality of orthogonal stepped surfaces 151 and aplurality of parallel stepped surfaces 152, wherein the orthogonalstepped surfaces 151 are orthogonal to the central axis and the parallelstepped surfaces 152 are parallel to the central axis. One of theorthogonal stepped surfaces is a groove bottom 153, and each of othertwo of the orthogonal stepped surfaces is a groove end 155. A distanceparallel to the central axis between the groove bottom 153 and the firstside portion 110 is smallest among distances parallel to the centralaxis between the orthogonal stepped surfaces 151 and the first sideportion 110. The two groove ends 155 are disposed on two ends of theannular grooves 150 respectively, and a distance parallel to the centralaxis between each of the two groove ends 155 and the first side portion110 is greater than distances parallel to the central axis between theorthogonal stepped surfaces 151 adjacent to thereof and the first sideportion 110. That is, the distance parallel to the central axis betweeneach of the two groove ends 155 and the first side portion 110 isgreater than distances parallel to the central axis between theorthogonal stepped surfaces 151 adjacent to thereof and the first sideportion 110, so each of the two groove ends 155 is the boundary of twoannular grooves 150 adjacent to each other. The boundary between twoannular grooves 150, which are adjacent to each other, is the same oneof the groove ends 155 (the same one of the orthogonal steppedsurfaces), wherein the foregoing one of the groove ends 155 is one ofthe orthogonal stepped surfaces included in two annular grooves 150which are adjacent to each other. When a number of the orthogonalstepped surfaces 151 of at least one of the annular grooves 150 is N2,the following condition can be satisfied: 4≦N2≦14. Therefore, it isfavorable for maintaining the effects of reducing the reflected lightsof the stepped surfaces of the annular grooves 150. Preferably, thefollowing condition can be satisfied: 5≦N2≦8.

Furthermore, when a sum of the orthogonal stepped surfaces 151 of eachof the annular grooves 150 is ΣN2, the following condition can besatisfied: 8≦ΣN2. Therefore, it is favorable for maintaining the effectsof reducing the reflected lights of the stepped surfaces of the annulargrooves 150.

In the 1st embodiment, when the distance parallel to the central axis ofeach of the annular grooves 150 between one of the two groove ends 155and the first side portion 110 is greater than the distance parallel tothe central axis between the other one of the two groove ends 155 andthe first side portion 110, and a distance parallel to the central axisbetween the one of the two groove ends 155 and the groove bottom 153 ish, the following condition can be satisfied: 0.02 mm<h<0.15 mm.Therefore, it is favorable for obtaining a significant surface structureof the annular grooves 150 so as to reduce the reflected lights andimprove the image quality.

In the 1st embodiment, when the distance parallel to the central axis ofeach of the annular grooves 150 between one of the two groove ends 155and the first side portion 110 is greater than the distance parallel tothe central axis between the other one of the two groove ends 155 andthe first side portion 110, a distance parallel to the central axisbetween the one of the two groove ends 155 and the groove bottom 153 ish, and a distance orthogonal to the central axis between the two grooveends 155 is d, the following condition can be satisfied: 0.15<h/d<1.6.Therefore, it is favorable for obtaining a proper proportion of thestepped surfaces of the annular grooves 150 so as to reduce the strengthof the reflected lights of the annular grooves 150.

FIG. 1E shows a schematic view of the parameter θ according to the 1stembodiment. In the 1st embodiment, when an angle between two linesconnecting the groove bottom 153 and the two groove ends 155respectively is θ, the following condition can be satisfied: 45degrees<θ<125 degrees. Therefore, it is favorable for the manufacturingyield rate of the annular optical spacer 100 and reducing themanufacturing difficulties.

The data of the aforementioned parameters of the annular optical spacer100 according to the 1st embodiment of the present disclosure are listedin the following Table 1. In Table 1, the sum of the orthogonal steppedsurfaces 151 of each of the annular grooves 150 of the annular opticalspacer 100 is ΣN2. Followed by showing the main ones of the annulargrooves 150 of the annular optical spacer 100, a number of the annulargrooves 150 which have the numbers of the orthogonal stepped surfaces151 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 151 of the annular grooves 150 aforementioned is N2,and the parameters h, d, h/d and θ are listed in Table 1 and shown asFIG. 1D and FIG. 1E.

TABLE 1 1st Embodiment φ1(mm) 5.35 N1 2 φ2(mm) 3.50 N2 6 φ2/φ1 0.65 h(mm) 0.045 φ1 − φ2 1.85 d (mm) 0.100 D (mm) 0.28 h/d 0.45 2D/(φ1 − φ2)0.30 θ (degrees) 106.0 ΣN2 >10

2nd Embodiment

FIG. 2A is a schematic view of an annular optical spacer 200 and theparameters φ1 and φ2 according to the 2nd embodiment of the presentdisclosure. In the 2nd embodiment, the annular optical spacer 200includes a first side portion 210, a second side portion 220, an outerannular portion 230 and an inner annular portion 240.

The second side portion 220 is disposed opposite to the first sideportion 210. The first side portion 210 and the second side portion 220include an abutting surface 211 and an abutting surface 221respectively, and the abutting surfaces 211, 221 are both flat andorthogonal to a central axis of the annular optical spacer 200. Theouter annular portion 230 connects the first side portion 210 and thesecond side portion 220. The inner annular portion 240 connects thefirst side portion 210 and the second side portion 220, wherein theinner annular portion 240 is closer to the central axis of the annularoptical spacer 200 than the outer annular portion 230. The inner annularportion 240 includes a plurality of annular grooves 250, wherein theannular grooves 250 are disposed coaxially to the central axis, and eachof the annular grooves 250 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 200 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 250 andthe annular optical spacer 200 are formed integrally.

FIG. 2B is an enlarged view of part 2B in FIG. 2A which shows theparameters D, h and d according to the 2nd embodiment. FIG. 2C shows aschematic view of the parameter θ according to the 2nd embodiment. Inthe 2nd embodiment, the stepped surfaces of each of the annular grooves250 include a plurality of orthogonal stepped surfaces 251 and aplurality of parallel stepped surfaces 252, wherein the orthogonalstepped surfaces 251 are orthogonal to the central axis and the parallelstepped surfaces 252 are parallel to the central axis. One of theorthogonal stepped surfaces 251 is a groove bottom 253, and each ofanother two of the orthogonal stepped surfaces 251 is a groove end 255.A distance parallel to the central axis between the groove bottom 253and the first side portion 210 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 251 and thefirst side portion 210. The two groove ends 255 are disposed on two endsof the annular grooves 250 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 200 according to the2nd embodiment of the present disclosure are listed in the followingTable 2. The definitions of these parameters shown in Table 2 are thesame as those stated in the 1st embodiment with corresponding values forthe 2nd embodiment. In Table 2, the sum of the orthogonal steppedsurfaces 251 of each of the annular grooves 250 of the annular opticalspacer 200 is ΣN2. Followed by showing the main ones of the annulargrooves 250 of the annular optical spacer 200, a number of the annulargrooves 250 which have the numbers of the orthogonal stepped surfaces251 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 251 of the annular grooves 250 aforementioned is N2,and the parameters h, d, h/d and θ are listed in Table 2 and shown asFIG. 2B and FIG. 2C.

TABLE 2 2nd Embodiment φ1(mm) 5.35 N1 3 φ2(mm) 3.50 N2 5 φ2/φ1 0.65 h(mm) 0.045 φ1 − φ2 1.85 d (mm) 0.080 D (mm) 0.30 h/d 0.56 2D/(φ1 − φ2)0.32 θ (degrees) 87.0 ΣN2 >10

3rd Embodiment

FIG. 3A is a schematic view of an annular optical spacer 300 and theparameters φ1 and φ2 according to the 3rd embodiment of the presentdisclosure. In the 3rd embodiment, the annular optical spacer 300includes a first side portion 310, a second side portion 320, an outerannular portion 330 and an inner annular portion 340.

The second side portion 320 is disposed opposite to the first sideportion 310. The first side portion 310 and the second side portion 320include an abutting surface 311 and an abutting surface 321respectively, and the abutting surface 311, 321 are both flat andorthogonal to a central axis of the annular optical spacer 300. Theouter annular portion 330 connects the first side portion 310 and thesecond side portion 320. The inner annular portion 340 connects thefirst side portion 310 and the second side portion 320, wherein theinner annular portion 340 is closer to the central axis of the annularoptical spacer 300 than the outer annular portion 330. The inner annularportion 340 includes a plurality of annular grooves 350, wherein theannular grooves 350 are disposed coaxially to the central axis, and eachof the annular grooves 350 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 300 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 350 andthe annular optical spacer 300 are formed integrally.

FIG. 3B is an enlarged view of part 3B in FIG. 3A which shows theparameters D, h and d according to the 3rd embodiment. FIG. 3C shows aschematic view of the parameter θ according to the 3rd embodiment. Inthe 3rd embodiment, the stepped surfaces of each of the annular grooves350 include a plurality of orthogonal stepped surfaces 351 and aplurality of parallel stepped surfaces 352, wherein the orthogonalstepped surfaces 351 are orthogonal to the central axis and the parallelstepped surfaces 352 are parallel to the central axis. One of theorthogonal stepped surfaces 351 is a groove bottom 353, and each ofanother two of the orthogonal stepped surfaces 351 is a groove end 355.A distance parallel to the central axis between the groove bottom 353and the first side portion 310 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 351 and thefirst side portion 310. The two groove ends 355 are disposed on two endsof the annular grooves 350 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 300 according to the3rd embodiment of the present disclosure are listed in the followingTable 3. The definitions of these parameters shown in Table 3 are thesame as those stated in the 1st embodiment with corresponding values forthe 3rd embodiment. In Table 3, the sum of the orthogonal steppedsurfaces 351 of each of the annular grooves 350 of the annular opticalspacer 300 is ΣN2. Followed by showing the main ones of the annulargrooves 350 of the annular optical spacer 300, a number of the annulargrooves 350 which have the numbers of the orthogonal stepped surfaces351 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 351 of the annular grooves 350 aforementioned is N2,the number of the annular grooves 350 (N1) which have the numbers of theorthogonal stepped surfaces 351 (N2) equaling to 6 respectively is 5,the number of the annular grooves 350 (N1) which have the numbers of theorthogonal stepped surfaces 351 (N2) equaling to 5 respectively is 3,and the corresponding parameters h, d, h/d and θ are listed in Table 3and shown as FIG. 3B and FIG. 3C.

TABLE 3 3rd Embodiment φ1(mm) 5.25 N1 8 φ2(mm) 3.20 N2 6 5 φ2/φ1 0.61 h(mm) 0.060 0.030 φ1 − φ2 2.05 d (mm) 0.050 0.040 D (mm) 0.51 h/d 1.200.75 2D/(φ1 − φ2) 0.49 θ (degrees) 67.0 67.0 ΣN2 >20

4th Embodiment

FIG. 4A is a schematic view of an annular optical spacer 400 and theparameters φ1 and φ2 according to the 4th embodiment of the presentdisclosure. In the 4th embodiment, the annular optical spacer 400includes a first side portion 410, a second side portion 420, an outerannular portion 430 and an inner annular portion 440.

The second side portion 420 is disposed opposite to the first sideportion 410. The first side portion 410 and the second side portion 420include an abutting surface 411 and an abutting surface 421respectively, and the abutting surface 411, 421 are both flat andorthogonal to a central axis of the annular optical spacer 400. Theouter annular portion 430 connects the first side portion 410 and thesecond side portion 420. The inner annular portion 440 connects thefirst side portion 410 and the second side portion 420, wherein theinner annular portion 440 is closer to the central axis of the annularoptical spacer 400 than the outer annular portion 430. The inner annularportion 440 includes a plurality of annular grooves 450, wherein theannular grooves 450 are disposed coaxially to the central axis, and eachof the annular grooves 450 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 400 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 450 andthe annular optical spacer 400 are formed integrally.

FIG. 4B is an enlarged view of part 4B in FIG. 4A which shows theparameters D, h and d according to the 4th embodiment. FIG. 4C shows aschematic view of the parameter θ according to the 4th embodiment. Inthe 4th embodiment, the stepped surfaces of each of the annular grooves450 include a plurality of orthogonal stepped surfaces 451 and aplurality of parallel stepped surfaces 452, wherein the orthogonalstepped surfaces 451 are orthogonal to the central axis and the parallelstepped surfaces 452 are parallel to the central axis. One of theorthogonal stepped surfaces 451 is a groove bottom 453, and each ofanother two of the orthogonal stepped surfaces 451 is a groove end 455.A distance parallel to the central axis between the groove bottom 453and the first side portion 410 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 451 and thefirst side portion 410. The two groove ends 455 are disposed on two endsof the annular grooves 450 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 400 according to the4th embodiment of the present disclosure are listed in the followingTable 4. The definitions of these parameters shown in Table 4 are thesame as those stated in the 1st embodiment with corresponding values forthe 4th embodiment. In Table 4, the sum of the orthogonal steppedsurfaces 451 of each of the annular grooves 450 of the annular opticalspacer 400 is ΣN2. Followed by showing the main ones of the annulargrooves 450 of the annular optical spacer 400, a number of the annulargrooves 450 which have the numbers of the orthogonal stepped surfaces451 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 451 of the annular grooves 450 aforementioned is N2,the number of the annular grooves 450 (N1) which have the numbers of theorthogonal stepped surfaces 451 (N2) equaling to 4 respectively is 5,the number of the annular grooves 450 (N1) which have the numbers of theorthogonal stepped surfaces 451 (N2) equaling to 6 respectively is 1,and the corresponding parameters h, d, h/d and θ are listed in Table 4and shown as FIG. 4B and FIG. 4C.

TABLE 4 4th Embodiment φ1(mm) 5.25 N1 6 φ2(mm) 3.20 N2 4 6 φ2/φ1 0.61 h(mm) 0.060 0.060 φ1 − φ2 2.05 d (mm) 0.045 0.075 D (mm) 0.50 h/d 1.330.80 2D/(φ1 − φ2) 0.49 θ (degrees) 59.0 59.0 ΣN2 >10

5th Embodiment

FIG. 5A is a schematic view of an annular optical spacer 500 and theparameters φ1 and φ2 according to the 5th embodiment of the presentdisclosure. In the 5th embodiment, the annular optical spacer 500includes a first side portion 510, a second side portion 520, an outerannular portion 530 and an inner annular portion 540.

The second side portion 520 is disposed opposite to the first sideportion 510. The first side portion 510 and the second side portion 520include an abutting surface 511 and an abutting surface 521respectively, and the abutting surface 511, 521 are both flat andorthogonal to a central axis of the annular optical spacer 500. Theouter annular portion 530 connects the first side portion 510 and thesecond side portion 520. The inner annular portion 540 connects thefirst side portion 510 and the second side portion 520, wherein theinner annular portion 540 is closer to the central axis of the annularoptical spacer 500 than the outer annular portion 530. The inner annularportion 540 includes a plurality of annular grooves 550, wherein theannular grooves 550 are disposed coaxially to the central axis, and eachof the annular grooves 550 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 500 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 550 andthe annular optical spacer 500 are formed integrally.

FIG. 5B is an enlarged view of part 5B in FIG. 5A which shows theparameters D, h and d according to the 5th embodiment. FIG. 5C shows aschematic view of the parameter θ according to the 5th embodiment. Inthe 5th embodiment, the stepped surfaces of each of the annular grooves550 include a plurality of orthogonal stepped surfaces 551 and aplurality of parallel stepped surfaces 552, wherein the orthogonalstepped surfaces 551 are orthogonal to the central axis and the parallelstepped surfaces 552 are parallel to the central axis. One of theorthogonal stepped surfaces 551 is a groove bottom 553, and each ofanother two of the orthogonal stepped surfaces 551 is a groove end 555.A distance parallel to the central axis between the groove bottom 553and the first side portion 510 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 551 and thefirst side portion 510. The two groove ends 555 are disposed on two endsof the annular grooves 550 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 500 according to the5th embodiment of the present disclosure are listed in the followingTable 5. The definitions of these parameters shown in Table 5 are thesame as those stated in the 1st embodiment with corresponding values forthe 5th embodiment. In Table 5, the sum of the orthogonal steppedsurfaces 551 of each of the annular grooves 550 of the annular opticalspacer 500 is ΣN2. Followed by showing the main ones of the annulargrooves 550 of the annular optical spacer 500, a number of the annulargrooves 550 which have the numbers of the orthogonal stepped surfaces551 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 551 of the annular grooves 550 aforementioned is N2,and the parameters h, d, h/d and θ corresponding to two kinds of theannular grooves 550 are respectively listed in Table 5 and shown as FIG.5B and FIG. 5C.

TABLE 5 5th Embodiment φ1(mm) 4.50 N1 4 φ2(mm) 2.45 N2 6 6 φ2/φ1 0.54 h(mm) 0.060 0.075 φ1 − φ2 2.05 d (mm) 0.100 0.100 D (mm) 0.50 h/d 0.600.75 2D/(φ1 − φ2) 0.48 θ (degrees) 103.0 100.0 ΣN2 >10

6th Embodiment

FIG. 6A is a schematic view of an annular optical spacer 600 and theparameters φ1 and φ2 according to the 6th embodiment of the presentdisclosure. In the 6th embodiment, the annular optical spacer 600includes a first side portion 610, a second side portion 620, an outerannular portion 630 and an inner annular portion 640.

The second side portion 620 is disposed opposite to the first sideportion 610. The first side portion 610 and the second side portion 620include an abutting surface 611 and an abutting surface 621respectively, and the abutting surface 611, 621 are both flat andorthogonal to a central axis of the annular optical spacer 600. Theouter annular portion 630 connects the first side portion 610 and thesecond side portion 620. The inner annular portion 640 connects thefirst side portion 610 and the second side portion 620, wherein theinner annular portion 640 is closer to the central axis of the annularoptical spacer 600 than the outer annular portion 630. The inner annularportion 640 includes a plurality of annular grooves 650, wherein theannular grooves 650 are disposed coaxially to the central axis, and eachof the annular grooves 650 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 600 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 650 andthe annular optical spacer 600 are formed integrally.

FIG. 6B is an enlarged view of part 6B in FIG. 6A which shows theparameters D, h and d according to the 6th embodiment. FIG. 6C shows aschematic view of the parameter θ according to the 6th embodiment. Inthe 6th embodiment, the stepped surfaces of each of the annular grooves650 include a plurality of orthogonal stepped surfaces 651 and aplurality of parallel stepped surfaces 652, wherein the orthogonalstepped surfaces 651 are orthogonal to the central axis and the parallelstepped surfaces 652 are parallel to the central axis. One of theorthogonal stepped surfaces 651 is a groove bottom 653, and each ofanother two of the orthogonal stepped surfaces 651 is a groove end 655.A distance parallel to the central axis between the groove bottom 653and the first side portion 610 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 651 and thefirst side portion 610. The two groove ends 655 are disposed on two endsof the annular grooves 650 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 600 according to the6th embodiment of the present disclosure are listed in the followingTable 6. The definitions of these parameters shown in Table 6 are thesame as those stated in the 1st embodiment with corresponding values forthe 6th embodiment. In Table 6, the sum of the orthogonal steppedsurfaces 651 of each of the annular grooves 650 of the annular opticalspacer 600 is ΣN2. Followed by showing the main ones of the annulargrooves 650 of the annular optical spacer 600, a number of the annulargrooves 650 which have the numbers of the orthogonal stepped surfaces651 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 651 of the annular grooves 650 aforementioned is N2,and the parameters h, d, h/d and θ are listed in Table 6 and shown asFIG. 6B and FIG. 6C.

TABLE 6 6th Embodiment φ1(mm) 6.50 N1 2 φ2(mm) 5.55 N2 10 φ2/φ1 0.85 h(mm) 0.120 φ1 − φ2 0.95 d (mm) 0.090 D (mm) 0.26 h/d 1.33 2D/(φ1 − φ2)0.55 θ (degrees) 67.0 ΣN2 >10

7th Embodiment

FIG. 7A is a schematic view of an annular optical spacer 700 and theparameters φ1 and φ2 according to the 7th embodiment of the presentdisclosure. In the 7th embodiment, the annular optical spacer 700includes a first side portion 710, a second side portion 720, an outerannular portion 730 and an inner annular portion 740.

The second side portion 720 is disposed opposite to the first sideportion 710. The first side portion 710 and the second side portion 720include an abutting surface 711 and an abutting surface 721respectively, and the abutting surface 711, 721 are both flat andorthogonal to a central axis of the annular optical spacer 700. Theouter annular portion 730 connects the first side portion 710 and thesecond side portion 720. The inner annular portion 740 connects thefirst side portion 710 and the second side portion 720, wherein theinner annular portion 740 is closer to the central axis of the annularoptical spacer 700 than the outer annular portion 730. The inner annularportion 740 includes a plurality of annular grooves 750, wherein theannular grooves 750 are disposed coaxially to the central axis, and eachof the annular grooves 750 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 700 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 750 andthe annular optical spacer 700 are formed integrally.

FIG. 7B is an enlarged view of part 7B in FIG. 7A which shows theparameters D, h and d according to the 7th embodiment. FIG. 7C shows aschematic view of the parameter θ according to the 7th embodiment. Inthe 7th embodiment, the stepped surfaces of each of the annular grooves750 include a plurality of orthogonal stepped surfaces 751 and aplurality of parallel stepped surfaces 752, wherein the orthogonalstepped surfaces 751 are orthogonal to the central axis and the parallelstepped surfaces 752 are parallel to the central axis. One of theorthogonal stepped surfaces 751 is a groove bottom 753, and each ofanother two of the orthogonal stepped surfaces 751 is a groove end 755.A distance parallel to the central axis between the groove bottom 753and the first side portion 710 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 751 and thefirst side portion 710. The two groove ends 755 are disposed on two endsof the annular grooves 750 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 700 according to the7th embodiment of the present disclosure are listed in the followingTable 7. The definitions of these parameters shown in Table 7 are thesame as those stated in the 1st embodiment with corresponding values forthe 7th embodiment. In Table 7, the sum of the orthogonal steppedsurfaces 751 of each of the annular grooves 750 of the annular opticalspacer 700 is ΣN2. Followed by showing the main ones of the annulargrooves 750 of the annular optical spacer 700, a number of the annulargrooves 750 which have the numbers of the orthogonal stepped surfaces751 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 751 of the annular grooves 750 aforementioned is N2,and the parameters h, d, h/d and θ corresponding to two kinds of theannular grooves 750 are respectively listed in Table 7 and shown as FIG.7B and FIG. 7C.

TABLE 7 7th Embodiment φ1(mm) 5.10 N1 5 φ2(mm) 3.05 N2 4 4 φ2/φ1 0.60 h(mm) 0.060 0.075 φ1 − φ2 2.05 d (mm) 0.075 0.075 D (mm) 0.63 h/d 0.801.00 2D/(φ1 − φ2) 0.62 θ (degrees) 82.0 93.0 ΣN2 >10

8th Embodiment

FIG. 8A is a schematic view of an annular optical spacer 800 and theparameters φ1 and φ2 according to the 8th embodiment of the presentdisclosure. In the 8th embodiment, the annular optical spacer 800includes a first side portion 810, a second side portion 820, an outerannular portion 830 and an inner annular portion 840.

The second side portion 820 is disposed opposite to the first sideportion 810. The first side portion 810 and the second side portion 820include an abutting surface 811 and an abutting surface 821respectively, and the abutting surface 811, 821 are both flat andorthogonal to a central axis of the annular optical spacer 800. Theouter annular portion 830 connects the first side portion 810 and thesecond side portion 820. The inner annular portion 840 connects thefirst side portion 810 and the second side portion 820, wherein theinner annular portion 840 is closer to the central axis of the annularoptical spacer 800 than the outer annular portion 830. The inner annularportion 840 includes a plurality of annular grooves 850, wherein theannular grooves 850 are disposed coaxially to the central axis, and eachof the annular grooves 850 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 800 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 850 andthe annular optical spacer 800 are formed integrally.

FIG. 8B is an enlarged view of part 8B in FIG. 8A which shows theparameters D, h and d according to the 8th embodiment. FIG. 8C shows aschematic view of the parameter θ according to the 8th embodiment. Inthe 8th embodiment, the stepped surfaces of each of the annular grooves850 include a plurality of orthogonal stepped surfaces 851 and aplurality of parallel stepped surfaces 852, wherein the orthogonalstepped surfaces 851 are orthogonal to the central axis and the parallelstepped surfaces 852 are parallel to the central axis. One of theorthogonal stepped surfaces 851 is a groove bottom 853, and each ofanother two of the orthogonal stepped surfaces 851 is a groove end 855.A distance parallel to the central axis between the groove bottom 853and the first side portion 810 is smallest among distances parallel tothe central axis between the orthogonal stepped surfaces 851 and thefirst side portion 810. The two groove ends 855 are disposed on two endsof the annular grooves 850 respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 800 according to the8th embodiment of the present disclosure are listed in the followingTable 8. The definitions of these parameters shown in Table 8 are thesame as those stated in the 1st embodiment with corresponding values forthe 8th embodiment. In Table 8, the sum of the orthogonal steppedsurfaces 851 of each of the annular grooves 850 of the annular opticalspacer 800 is ΣN2. Followed by showing the main ones of the annulargrooves 850 of the annular optical spacer 800, a number of the annulargrooves 850 which have the numbers of the orthogonal stepped surfaces851 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 851 of the annular grooves 850 aforementioned is N2,and the parameters h, d, h/d and θ are listed in Table 8 and shown asFIG. 8B and FIG. 8C.

TABLE 8 8th Embodiment φ1(mm) 5.30 N1 3 φ2(mm) 3.86 N2 4 φ2/φ1 0.73 h(mm) 0.060 φ1 − φ2 1.44 d (mm) 0.045 D (mm) 0.22 h/d 1.33 2D/(φ1 − φ2)0.31 θ (degrees) 72.0 ΣN2 >10

9th Embodiment

FIG. 9A is a schematic view of an annular optical spacer 900 and theparameters φ1, φ2 and D according to the 9th embodiment of the presentdisclosure. In the 9th embodiment, the annular optical spacer 900includes a first side portion 910, a second side portion 920, an outerannular portion 930 and an inner annular portion 940.

The second side portion 920 is disposed opposite to the first sideportion 910. The first side portion 910 and the second side portion 920include an abutting surface 911 and an abutting surface 921respectively, and the abutting surface 911, 921 are both flat andorthogonal to a central axis of the annular optical spacer 900. Theouter annular portion 930 connects the first side portion 910 and thesecond side portion 920. The inner annular portion 940 connects thefirst side portion 910 and the second side portion 920, wherein theinner annular portion 940 is closer to the central axis of the annularoptical spacer 900 than the outer annular portion 930. The inner annularportion 940 includes a plurality of annular grooves 950, wherein theannular grooves 950 are disposed coaxially to the central axis, and eachof the annular grooves 950 includes a plurality of stepped surfaces (itsreference numeral is omitted).

The annular optical spacer 900 is made of black plastic material andmanufactured by an injection molding method. The annular grooves 950 andthe annular optical spacer 900 are formed integrally.

FIG. 9B is an enlarged view of part 9B in FIG. 9A which shows theparameters h and d according to the 9th embodiment. FIG. 9C shows aschematic view of the parameter θ according to the 9th embodiment. FIG.9D is an enlarged view of part 9D in FIG. 9A which shows the parametersh and d according to the 9th embodiment. FIG. 9E shows another schematicview of the parameter θ according to the 9th embodiment. In the 9thembodiment, FIG. 9B and FIG. 9C show one of the annular grooves 950 ofthe annular optical spacer 900, and FIG. 9D and FIG. 9E show another ofthe annular grooves 950 of the annular optical spacer 900. The steppedsurfaces of each of the annular grooves 950 include a plurality oforthogonal stepped surfaces 951 and a plurality of parallel steppedsurfaces 952, wherein the orthogonal stepped surfaces 951 are orthogonalto the central axis and the parallel stepped surfaces 952 are parallelto the central axis. One of the orthogonal stepped surfaces 951 is agroove bottom 953, and each of another two of the orthogonal steppedsurfaces 951 is a groove end 955. A distance parallel to the centralaxis between the groove bottom 953 and the first side portion 910 issmallest among distances parallel to the central axis between theorthogonal stepped surfaces 951 and the first side portion 910. The twogroove ends 955 are disposed on two ends of the annular grooves 950respectively.

The data of the parameters φ1, φ2, φ2/φ1, φ1−φ2, D, 2D/(φ1−φ2), ΣN2, N1,N2, h, d, h/d and θ of the annular optical spacer 900 according to the9th embodiment of the present disclosure are listed in the followingTable 9. The definitions of these parameters shown in Table 9 are thesame as those stated in the 1st embodiment with corresponding values forthe 9th embodiment. In Table 9, the sum of the orthogonal steppedsurfaces 951 of each of the annular grooves 950 of the annular opticalspacer 900 is ΣN2. Followed by showing the main ones of the annulargrooves 950 of the annular optical spacer 900, a number of the annulargrooves 950 which have the numbers of the orthogonal stepped surfaces951 equaling to 4 to 14 respectively is N1, the number of the orthogonalstepped surfaces 951 of the annular grooves 950 aforementioned is N2,the number of the annular grooves 950 (N1) which have the numbers of theorthogonal stepped surfaces 951 (N2) equaling to 5 respectively is 34,the number of the annular grooves 950 (N1) which have the numbers of theorthogonal stepped surfaces 951 (N2) equaling to 6 respectively is 2,and the corresponding parameters h, d, h/d and θ are listed in Table 9and shown as FIG. 9B, FIG. 9C, FIG. 9D and FIG. 9E.

TABLE 9 9th Embodiment φ1(mm) 13.50 N1 36 φ2(mm) 7.15 N2 5 6 φ2/φ1 0.53h (mm) 0.045 0.045 φ1 − φ2 6.35 d (mm) 0.040 0.050 D (mm) 1.58 h/d 1.130.90 2D/(φ1 − φ2) 0.50 θ (degrees) 67.0 67.0 ΣN2 >40

10th Embodiment

FIG. 10 shows an imaging lens module 1000 according to the 10thembodiment of the present disclosure. In the 10th embodiment, theimaging lens module 1000 includes a barrel 1100, a lens assembly 1200,and the annular optical spacer 100.

The lens assembly 1200 includes a plurality of lens elements (1210-1250)disposed in the barrel 1100.

In FIG. 1C, FIG. 1D and FIG. 1E, the annular optical spacer 100 includesthe first side portion 110, the second side portion 120, the outerannular portion 130 and the inner annular portion 140. The second sideportion 120 is disposed opposite to the first side portion 110. Theouter annular portion 130 connects the first side portion 110 and thesecond side portion 120. The inner annular portion 140 connects thefirst side portion 110 and the second side portion 120, wherein theinner annular portion 140 is closer to the central axis of the annularoptical spacer 100 than the outer annular portion 130. The inner annularportion 140 includes the annular grooves 150, wherein the annulargrooves 150 are disposed coaxially to the central axis, and each of theannular grooves 150 includes the stepped surfaces. Therefore, it isfavorable for reducing the reflected lights effectively so as to improvethe image quality. The other details of the annular optical spacer 100have been described in the foregoing paragraphs and will not be repeatedherein.

In details, the lens assembly 1200 includes the first lens element 1210,the second lens element 1220, the third lens element 1230, the fourthlens element 1240 and the fifth lens element 1250, wherein the fifthlens element 1250 is closest to an image plane of the imaging lensmodule 1000, and the fourth lens element 1240 is secondary closest tothe image plane of the imaging lens module 1000. The annular opticalspacer 100 is disposed between the fourth lens element 1240 and thefifth lens element 1250. The abutting surface 121 of the second sideportion 120 abuts with a light limiting element (its reference numeralis omitted) next to the fifth lens element 1250. That is, the abuttingsurface 121 of the second side portion 120 abuts with the fifth lenselement 1250 indirectly, and the abutting surface 111 of the first sideportion 110 abuts with the fourth lens element 1240 directly. Therefore,it is favorable for stably maintaining an abutting strength so as toimprove the image quality of the imaging lens module 1000.

Furthermore, in other embodiment, an imaging lens module can include atleast two optical elements such as lens elements. The annular opticalspacer can include two abutting surfaces respectively disposed on afirst side portion and a second side portion, wherein the abuttingsurfaces are orthogonal to a central axis of the annular optical spacerand abut with one of the optical elements respectively.

Moreover, the imaging lens module can include at least two lenselements. One of the two abutting surfaces of the annular optical spacerabuts with one of the lens elements, which is closest to an image planeof the imaging lens module among lens elements. The other of the twoabutting surfaces of the annular optical spacer abuts with another ofthe lens elements, which is secondary closest to the image plane of theimaging lens module among lens elements.

11th Embodiment

FIG. 11 shows an electronic device 10 according to the 11th embodimentof the present disclosure. The electronic device 10 of the 11thembodiment is a smart phone, wherein the electronic device 10 includesan imaging apparatus 11, the imaging apparatus 11 includes an imaginglens module (not shown) according to the present disclosure and an imagesensor (not shown), and the imaging lens module includes an annularoptical spacer (not shown) according to the present disclosure.Therefore, it is favorable for reducing the reflected lights effectivelyso as to improve the image quality and satisfy the requirements ofhigh-end electronic devices with camera functionalities. Furthermore,the image sensor is disposed on or near an image surface of the imaginglens module. Preferably, the electronic device 10 can further includebut not limited to a display, a control unit, a storage unit, a randomaccess memory unit (RAM), a read-only memory unit (ROM) or a combinationthereof.

12th Embodiment

FIG. 12 shows an electronic device 20 according to the 12th embodimentof the present disclosure. The electronic device 20 of the 12thembodiment is a tablet personal computer, wherein the electronic device20 includes an imaging apparatus 21, the imaging apparatus 21 includesan imaging lens module (not shown) according to the present disclosureand an image sensor (not shown), the imaging lens module includes anannular optical spacer (not shown) according to the present disclosure,and the image sensor is disposed on or near an image surface of theimaging lens module.

13th Embodiment

FIG. 13 shows an electronic device 30 according to the 13th embodimentof the present disclosure. The electronic device 30 of the 13thembodiment is a head-mounted display, wherein the electronic device 30includes an imaging apparatus 31, the imaging apparatus 31 includes animaging lens module (not shown) according to the present disclosure andan image sensor (not shown), the imaging lens module includes an annularoptical spacer (not shown) according to the present disclosure, and theimage sensor is disposed on or near an image surface of the imaging lensmodule.

Although the present disclosure has been described in considerabledetail with reference to the embodiment thereof, other embodiments arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the embodiment contained herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the presentdisclosure. In view of the foregoing, it is intended that the presentdisclosure cover modifications and variations of this disclosureprovided they fall within the scope of the following claims.

What is claimed is:
 1. An annular optical spacer, comprising: a firstside portion; a second side portion disposed opposite to the first sideportion; an outer annular portion connecting the first side portion andthe second side portion; and an inner annular portion connecting thefirst side portion and the second side portion, wherein the innerannular portion is closer to a central axis of the annular opticalspacer than the outer annular portion is to the central axis, andcomprises: a plurality of annular grooves, wherein the annular groovesare disposed coaxially to the central axis, and each of the annulargrooves comprises a plurality of stepped surfaces; wherein the steppedsurfaces of each of the annular grooves comprise a plurality oforthogonal stepped surfaces orthogonal to the central axis, a number ofthe orthogonal stepped surfaces of at least one of the annular groovesis N2, and the following condition is satisfied:4≦N2≦14.
 2. The annular optical spacer of claim 1, wherein the annulargrooves and the annular optical spacer are formed integrally.
 3. Theannular optical spacer of claim 2, wherein each of the first sideportion and the second side portion comprises an abutting surface, andeach of the abutting surfaces is flat and orthogonal to the central axisof the annular optical spacer.
 4. The annular optical spacer of claim 3,wherein one of the orthogonal stepped surfaces is a groove bottom, andeach of another two of the orthogonal stepped surfaces is a groove end;wherein a distance parallel to the central axis between the groovebottom and the first side portion is smallest among distances parallelto the central axis between the orthogonal stepped surfaces and thefirst side portion, the two groove ends are disposed on two ends of theannular grooves respectively, and a distance parallel to the centralaxis between each of the two groove ends and the first side portion isgreater than distances parallel to the central axis between theorthogonal stepped surfaces adjacent to thereof and the first sideportion; wherein the distance parallel to the central axis between oneof the two groove ends and the first side portion is greater than thedistance parallel to the central axis between the other one of the twogroove ends and the first side portion, a distance parallel to thecentral axis between the one of the two groove ends and the groovebottom is h, and the following condition is satisfied:0.02 mm<h<0.15 mm.
 5. The annular optical spacer of claim 3, wherein oneof the orthogonal stepped surfaces is a groove bottom, and each ofanother two of the orthogonal stepped surfaces is a groove end; whereina distance parallel to the central axis between the groove bottom andthe first side portion is smallest among distances parallel to thecentral axis between the orthogonal stepped surfaces and the first sideportion, the two groove ends are disposed on two ends of the annulargrooves respectively, and a distance parallel to the central axisbetween each of the two groove ends and the first side portion isgreater than distances parallel to the central axis between theorthogonal stepped surfaces adjacent to thereof and the first sideportion; wherein the distance parallel to the central axis between oneof the two groove ends and the first side portion is greater than thedistance parallel to the central axis between the other one of the twogroove ends and the first side portion, a distance parallel to thecentral axis between the one of the two groove ends and the groovebottom is h, a distance orthogonal to the central axis between the twogroove ends is d, and the following condition is satisfied:0.15<h/d<1.6.
 6. The annular optical spacer of claim 3, wherein one ofthe orthogonal stepped surfaces is a groove bottom, and each of anothertwo of the orthogonal stepped surfaces is a groove end; wherein adistance parallel to the central axis between the groove bottom and thefirst side portion is smallest among distances parallel to the centralaxis between the orthogonal stepped surfaces and the first side portion,the two groove ends are disposed on two ends of the annular groovesrespectively, and a distance parallel to the central axis between eachof the two groove ends and the first side portion is greater thandistances parallel to the central axis between the orthogonal steppedsurfaces adjacent to thereof and the first side portion; wherein anangle between two lines connecting the groove bottom and the two grooveends respectively is θ, and the following condition is satisfied:45 degrees<θ<125 degrees.
 7. The annular optical spacer of claim 2,wherein the annular optical spacer is made of black plastic material andmanufactured by an injection molding method.
 8. The annular opticalspacer of claim 3, wherein an outer diameter of the annular opticalspacer is φ1, an inner diameter of the annular optical spacer is φ2, andthe following condition is satisfied:0.40<φ2/φ1<0.90.
 9. The annular optical spacer of claim 3, wherein adistance between an end closest to the central axis and an end farthestaway from the central axis of the annular grooves is D, an outerdiameter of the annular optical spacer is φ1, an inner diameter of theannular optical spacer is φ2, and the following condition is satisfied:0.15<2D/(φ1−φ2)<0.80.
 10. The annular optical spacer of claim 1, whereinthe number of the orthogonal stepped surfaces of at least one of theannular grooves is N2, and the following condition is satisfied:5≦N2≦8.
 11. The annular optical spacer of claim 1, wherein a number ofthe annular grooves is N1, and the following condition is satisfied:2≦N1≦50.
 12. The annular optical spacer of claim 11, wherein the numberof the annular grooves is N1, and the following condition is satisfied:2≦N1≦10.
 13. The annular optical spacer of claim 1, wherein a sum of theorthogonal stepped surfaces of every one of the annular grooves is ΣN2,and the following condition is satisfied:8≦ΣN2.
 14. An imaging lens module, comprising: a barrel; a lensassembly, which comprises a plurality of lens elements disposed in thebarrel; and an annular optical spacer, which is disposed in the barreland connects to at least one of the lens elements, wherein the annularoptical spacer comprises: a first side portion; a second side portiondisposed opposite to the first side portion; an outer annular portionconnecting the first side portion and the second side portion; and aninner annular portion connecting the first side portion and the secondside portion, wherein the inner annular portion is closer to a centralaxis of the annular optical spacer than the outer annular portion is tothe central axis, and comprises: a plurality of annular grooves, whereinthe annular grooves are disposed coaxially to the central axis, and eachof the annular grooves comprises a plurality of stepped surfaces;wherein the stepped surfaces of each of the annular grooves comprise aplurality of orthogonal stepped surfaces orthogonal to the central axis,a sum of the orthogonal stepped surfaces of every one of the annulargrooves is ΣN2, and the following condition is satisfied:8≦ΣN2.
 15. An imaging apparatus, comprising: the imaging lens module ofclaim
 14. 16. An electronic device, comprising: the imaging apparatus ofclaim 15.